The 9.3x72R Sauer is a bottle necked case. I don't have my book with dimensions at hand but I don't believe there is any part of that chamber which is smaller than the regular 9.3x72R cartridge. The head diameter is definitely larger so the regular 9.3x72R would be a loose fit there.
I highly suspect that the 9x72R is the correct answer. A 118.35ga translates to a "Bore" diameter which will accept a plug gage of .340" but not one of .350" (108.45ga) which could be proper for either the 9mm or the 9.3mm. Gun was likely built prior to 1912.
